CCNA IP Routing Practice Test 17 — 15 Questions

Question 1

Exhibit: R3 learns 10.50.0.0/16 by OSPF through two equal-cost paths. What will R3 do by default?

Accepted Answer

Install both routes and load balance. When OSPF has equal-cost routes to the same destination, the router installs multiple paths and can load balance across them, assuming the platform supports the default maximum-paths value.

Answer

Choose the route from the neighbor with the highest router ID only

Answer

Install only one route because OSPF does not support ECMP

Answer

Prefer the path with the lower next-hop IP address

Question 2

Exhibit: A router has the following routes in its routing table:
- OSPF: 10.1.1.0/24
- Static: 10.1.1.128/25
- Default: 0.0.0.0/0

A packet is destined for 10.1.1.130. Which route does the router use?

Accepted Answer

The static 10.1.1.128/25 route. Routers use longest-prefix match before they think about metrics. The /25 route for 10.1.1.128/25 is more specific than the /24 or the default route, so traffic for 10.1.1.130 follows that path.

Answer

The OSPF 10.1.1.0/24 route

Answer

The default route

Answer

The router load-balances across all three

Question 3

Exhibit: R1 has a static default route to 192.0.2.2 and also learns a default route from OSPF. Which default route is installed in the routing table?

Accepted Answer

The static default route because its administrative distance is lower. When two routes to the same prefix are learned from different sources, the router compares administrative distance first. A static route has AD 1 by default, while OSPF has AD 110, so the static default route wins unless its AD was changed manually.

Answer

The OSPF default route because dynamic routes are preferred

Answer

Both default routes because they have the same prefix length

Answer

Neither route until a floating static route is configured

Question 4

A router advertises its LAN network into OSPF, but no OSPF Hellos should be sent toward end-user devices on that LAN. Which configuration approach solves this cleanly?

Accepted Answer

Configure the LAN interface as a passive interface in OSPF. A passive interface advertises the connected subnet into OSPF without sending or processing Hellos on that interface. That is exactly what you want for user-facing LANs with no OSPF neighbors.

Answer

Use ip ospf cost 65535 on the LAN interface

Answer

Disable OSPF globally and redistribute connected routes

Answer

Convert the LAN interface to a loopback

Question 5

On a broadcast multiaccess segment, R3 has an OSPF priority of 255, but it is in the DROTHER state. Which explanation best fits OSPF behavior?

Accepted Answer

DR election is nonpreemptive on broadcast networks. On broadcast networks, OSPF DR and BDR election is not preemptive. If a DR is already elected, giving another router a higher priority later does not force a new election unless the current DR goes down or OSPF is reset on the segment.

Answer

A router cannot become DR if it uses a loopback router ID

Answer

OSPF priority works only on point-to-point links

Answer

R3's priority is lower than the current DR's priority

Question 6

R1 is not forming an OSPF adjacency with R2 on GigabitEthernet0/1. Which mismatch below is the most likely cause?

Accepted Answer

The routers are using different IP subnet masks on the shared link. For OSPF neighbors to form, key settings on a shared segment must match. A subnet mask mismatch on a broadcast network often prevents proper neighbor formation because the routers do not agree on the local network.

Answer

OSPF cannot run on GigabitEthernet interfaces

Answer

Both routers are in area 0

Answer

The router IDs must match for adjacency to form

Question 7

Exhibit: OSPF neighbors are not reaching FULL state on an Ethernet segment with multiple routers. The output of show ip ospf neighbor on R2 shows a neighbor in the 2WAY/DROTHER state. What is the most likely reason?

Accepted Answer

The 2WAY state with another DROTHER on a broadcast segment is normal. On a broadcast Ethernet network, two routers normally become fully adjacent through the DR or BDR. If the local router is stuck in 2WAY with another DROTHER, that is normal behavior. It is not a fault by itself.

Answer

Authentication mismatch between R2 and 3.3.3.3

Answer

R2 must be configured as a point-to-point network type

Answer

R2 has a duplicate router ID

Question 8

Exhibit: R1 has learned 10.50.0.0/24 through OSPF and also has a floating static route to the same prefix with administrative distance 130. Which route is installed while OSPF is healthy?

Accepted Answer

The OSPF route because its administrative distance is lower than the floating static route. A floating static route is meant to stay out of the table until the preferred route disappears. OSPF has administrative distance 110, which is lower than the static route AD 130, so the OSPF route is installed while the OSPF path is still present.

Answer

The static route because static routes always win over dynamic routes

Answer

Both routes because the prefix length matches

Answer

Neither route until equal-cost load balancing is configured

Question 9

R3 has the static route 'ip route 172.20.8.0 255.255.255.0 192.168.1.1'. Packets destined for 172.20.8.0/24 are being dropped. What is the most likely cause?

Accepted Answer

The next-hop address is not reachable from R3. A static route can only work if the next-hop address is reachable. If the next hop is down or missing from the routing table, the route cannot forward traffic successfully.

Answer

The destination network mask should be /16 instead of /24

Answer

Static routes require an outbound access list

Answer

The route must use administrative distance 255

Question 10

A network engineer wants a static route to be used only when the OSPF-learned route disappears. Which configuration approach meets that goal?

Accepted Answer

Use a static route with administrative distance higher than 110. That is a floating static route. You configure the static route with an administrative distance higher than the OSPF route so it stays in reserve until the dynamic path is lost.

Answer

Use a static route with administrative distance 1

Answer

Use a static route with metric 0

Answer

Redistribute the static route into OSPF

Question 11

Exhibit: R1 shows an OSPF neighbor stuck in EXSTART with R2 on a serial link. What is the most likely cause?

Accepted Answer

An interface MTU mismatch between the routers. When two OSPF routers stay in EXSTART, the first thing to suspect is an MTU mismatch. They can discover each other, but database exchange does not complete because the DBD packets do not agree on interface MTU.

Answer

An OSPF area mismatch

Answer

A duplicate router ID on R1 and R2

Answer

A missing default route on R2

Question 12

Which OSPF component is used to identify routers uniquely inside an OSPF domain?

Accepted Answer

Router ID. The router ID is the unique identifier OSPF uses for each router. It is not the same thing as the process ID, which is locally significant only.

Answer

Area ID

Answer

Hello timer

Answer

Wildcard mask

Question 13

R1 has routes to 172.16.10.0/24 from multiple sources. Which route will be installed?

Accepted Answer

The EIGRP internal route. Routers compare route source trust first using administrative distance. EIGRP internal routes have an AD of 90, which is lower than OSPF (110), RIP (120), and a static route with AD 95. Therefore, the EIGRP internal route is installed, regardless of metrics.

Answer

The OSPF route with metric 20

Answer

The RIP route because hop count is lowest

Answer

The static route with administrative distance 95

Question 14

Exhibit: R1 learns 192.168.50.0/24 from multiple sources. Which two statements are correct about the route that will be installed in the routing table?

Accepted Answer

The static route is preferred because its administrative distance is lowest. The router chooses the route with the lowest administrative distance first. If administrative distance ties, it then compares the metric within that routing source. In this case the static route wins because AD 1 beats eBGP 20, OSPF 110, and RIP 120.

Answer

The OSPF route is preferred because cost 20 is lower than RIP metric 2

Answer

The eBGP route would win over the static route because BGP is more dynamic

Answer

RIP would be chosen before OSPF because hop count is simpler

Question 15

Exhibit: A router has both an OSPF-learned default route and a floating static default route. Which route is currently active?

Accepted Answer

The OSPF default route, because AD 110 beats the floating static AD 150. A floating static route only takes over when its administrative distance is set higher than the preferred route and the preferred route disappears. The routing table shows the OSPF default because AD 110 is lower than the floating static AD 150.

Answer

The static route, because static routes always override dynamic routes

Answer

Both routes load-balance automatically

Answer

Neither route, because a default route cannot be learned by OSPF